Foam sponges manufactured from materials such as gelatin or collagen are commonly used to control bleeding which occurs during surgery. These products range in size, typically from 10 mm×10 mm up to 80 mm×120 mm, with a thickness ranging typically from 2 mm to 10 mm. They are made from bioresorbable materials so they can be left in situ in, or on, the body. Commercially available products include Surgifoam (Ethicon), Gelfoam (Pfizer), Ultrafoam (Bard-Davol) and GelitaSpon (Gelita).
Foam sponges control bleeding by providing a porous matrix that adsorbs blood, and provides a surface that promotes clotting. Clotting factors may also be concentrated as the matrix of the sponge absorbs fluid. These products are reasonably effective and widely used in surgery. They may be used dry, or wetted with saline, or to increase efficacy they may be wetted with a solution of the coagulating enzyme, thrombin or other coagulating agents.
There are certain types of surgery where greater adhesion of the product to the tissue or organ is desirable to ensure it stays in place. Surgical procedures, such as open liver resections, where the sponge is not held in place by surrounding tissue, is one such example. In addition, where a sponge is applied to a partially dry wound or a lightly bleeding wound, there may be insufficient blood clotting to adhere the sponge to the wound.
To address both these concerns, products have been developed in which thrombin and the fibrinogen are dried on the sponge. When such products are applied to a wound the agents dissolve, react and form an adhesive film. The film effectively adheres the product to tissues or organs. An example of such a product is Tachosil (Takeda). Another approach has been to coat synthetic chemicals onto the product to chemically bond it to tissue via a reactive group (e.g. Hemopatch, Baxter). However, a major disadvantage of such products is the associated cost. For example, these products can cost between three and fifteen times the price of regular sponges. Another disadvantage is the risk of exposure of the patient to unidentified blood contaminants, particularly in the case of products with blood-derived thrombin and fibrinogen.